4/4/2016

1

Chapter 15Urinary SystemUrinary SystemUrinary SystemUrinary System

A major system responsible for

eliminating waste from the body.

What other systems eliminate waste?

Major Functions of Urinary System

� Eliminate nitrogenous waste, toxins, & excess ions

� Regulate volume, pressure, & chemical balance of blood

� Stimulate bones to make RBCs

Urine is a product of all of these functions

The Kidneys: Location� Protection from ribs� Liver causes right kidney to be lower

� Retroperitoneal position in the posterior-superior abdominal

cavity

Kidney Size

� About the size of a computer mouse

External Anatomy of Kidneys

� Renal Fascia – connective tissue that holds kidneys against dorsal muscles

� Perirenal adipose capsule – layer of fat surrounding kidneys that act as cushion

� Renal capsule – transparent tissue that encloses kidney tissues

Renal capsule

Renal fascia

Internal Anatomy of Kidneys

�3 Major Regions:

1) Outer

RENAL CORTEX

2) Middle

RENAL MEDULLA

3) Inner

RENALPELVIS

4/4/2016

2

Renal Cortex

�Outermost layer of kidney

�Contains blood vessels and parts of nephrons

Renal Medulla

�Middle layer of kidney

�Made up of triangular regions, called renal pyramids, with renal columns in between.

Renal pyramid

Renal column

Renal Pelvis

� Innermost layer of kidney

� Connects to ureter

� Has branching extensions, called calyces, that attach to pyramids to collect urine from nephrons

Blood Supply to Kidneys� ~25% of your blood passes through your kidneys each minute!

� Renal arteries – bring blood into kidneys & narrow in the renal cortex

� Renal veins – carry filtered and deoxygenated blood out of kidneys

Think & Review

1. The kidneys are retroperitoneal. What does that mean?

2. Carrie lost lots of weight, and suddenly she was having problems with her urine flow. Why would weight loss interfere with urine flow?

3. Name the 3 major regions of the kidney, from superficial to deep.

Nephrons:

� The major structural & functional units of kidneys where blood is filtered to form urine.

(Each kidney contains over 1 million nephrons!)

4/4/2016

3

Nephrons:� Each one contains:

1) A glomerulus – a knot of blood capillaries where blood is filtered

2) A renal tubule – long, winding tube that transports “filtrate” toward ureter (produces urine)

Basic Nephron Anatomy Urine Formation

� 3 major processes:

1) Glomerular Filtration – blood pressure from arteries forces water and other tiny molecules out of capillary and into glomerular (Bowman’s) capsule.

2) Tubular Reabsorption – as filtrate travels through renal tubule, needed molecules (mainly water) get reabsorbed back into blood vessel while nitrogenous waste remains in tubules.

3) Tubular Secretion – any drugs or excess ions are secreted back into the filtrate in renal tubule to be eliminated.

Review: Controlled by ADH

Urine FormationWhat color is “ur(ine)” pee pee?

�Why is it yellow?

� Worn out RBC’s are destroyed in the spleen. The remaining hemoglobin gets broken down into particles, called urochrome.They are no longer able to carry oxygen and take on a yellowish appearance. The particles are filtered out in the kidneys and are eliminated in urine.

4/4/2016

4

Urine Color Chart

That’s blood… Call the doctor!!

You might be taking vitamin supplements

SeverelySeverelySeverelySeverely

dehydrated!dehydrated!dehydrated!dehydrated!

Overhydrated?

Other Urinary Organs� Ureters = tubes that carry urine from renal pelvis to urinary bladder

� Urinary bladder = muscular sac that stores urine until it is released

REVIEW:

What type of “stretchy” epithelial tissue makes up the urinary bladder?

� Urethra = tube that transports urine to outside of body

Excretory F.Y.I.� Kidney Stones (AKA renal calculi) – occurs when urine becomes hyper-concentrated with uric acid/calcium crystals that collect in the renal pelvis

PAIN = when sharp crystals are passed along ureters

Causes:• Long-term dehydration• Diet: too much…

• Salt• Sugar• Calcium• Vitamin D

• Medical problems• Genetics

Review� What is the first nephronic structure that filters the blood to produce urine?

� What gets “reabsorbed” during tubular reabsorption?

� Which hormone regulates the reabsorption process?

� (Review) John’s doctor tests his urine and finds traces of bile pigments in his urine. What does this indicate? (which organ has a problem?)

� Which urinary organ transports urine from the bladder to exit the body?